The original Jesus is 40 years old now. That is, the original Jesus of the National Center of Afro-American Artists' "Black Nativity."

"The first live Baby Jesus works backstage in the show," says Voncille Ross, executive director of the show. "His 6-year-old daughter was Baby Jesus, and she now sings in the show."

This Boston holiday tradition is the longest-running production of "Black Nativity" in the world, beginning in 1969. (They didn't use a live baby for the first few years.) Ross says that once people begin performing in "Black Nativity," they usually continue with it.

"It's such a family feel," says Ross. "It's so many generations of families that are involved in 'Black Nativity.' It's a legacy we just want to keep alive. At one point, we realize it has to end. But we want to keep it going as long as it can."

Ross began singing as a part of the chorus when she was 12. Before becoming executive director, she had been the narrator and a stage manager.

"Since I was so young when I began in the production, Christmas is just not Christmas without 'Black Nativity' for me," she says. "The songs are just heartfelt, a rhythm that you keep and a beat that you keep. And those are songs we learned as children in school, like 'Go Tell it On the Mountain' and 'Joy to the World,' but they have a snazzier, jazzier beat."

Snazzier and jazzier are an understatement. The narrative combines the Gospel of Luke with the eloquent poetry of Langston Hughes and gospel music so soul-stirring that it could convert even the most devout atheist.

"You really feel the story and you connect with it," says Ross. "A lot of the songs are through the black gospel tradition, and gospel music is just so uplifting."